In the process of manufacturing semiconductor devices the usable chips cut or diced from the wafer are bonded to substrates/leadframe. Bond wires or other connecting means are connected between contacts on the chip and lead lines on the substrate/leadframe to form a semiconductor assembly. This semiconductor assembly of semiconductor chip, bond wires or other connecting means and the substrate/leadframe leads closest to the chip are encapsulated in a plastic mold compound using a mold press die machine as illustrated in FIG. 1. FIG. 1 illustrates encapsulating the semiconductor assembly 12 of chip, bond wires and substrate/leadframe leads closest to the chip. Sometimes the underside of the substrate/leadframe is not encapsulated to allow the bottom to be heat sinked. The molded semiconductor assembly 12 is then trimmed to form the finished devices.
A current mold press die machine in order to increase production is made large in size with a broad planar surface to handle multiple substrate/leadframes as illustrated by FIGS. 2-4. This current mold press die machine 10 has an upper mold die half 11 and a lower mold die half 13. FIG. 2 illustrates a front vertical view of the current planar mold die machine 10 and FIG. 3 illustrates a side vertical view of the current planar mold die machine 10. FIG. 4 illustrates a plan view of the inner (under) surface 11a of the molding die half 11 to show the mold. The inner upper mold die half 11 of the die machine 10 has four substrate/leadframe molding die sections 15-18 for molding four substrate/leadframes 101-104 simultaneously. Each of the sections 15-18 has three recesses or molding pockets 14 surrounded by a frame mold 24 for receiving and encapsulating three semiconductor assemblies 12 therein as described above wherein the assemblies include the chip, bond wires and chip adjacent portion lead wires on substrate/leadframes 101-104. FIG. 2 illustrates the front molding die sections 15 and 16 about set of substrate/leadframes represented by 101 and 102. FIG. 3 illustrates the side sections 16 and 18 above assemblies 12 on substrate/leadframes represented by 102 and 104. Although not shown in FIG. 4 but shown in FIGS. 2 and 3 there are through the upper die half 11 die halls or apertures 19 through the die half 11 at each assembly 12 location (at the pockets 14) to pass heated plastic mold compound 20 into mold die machine 10 to at the pockets 14 to, when the halves 11 and 13 are pressed, mold and encapsulate the semiconductor assembly 12 on the substrate/leadframes 101-104. This machine 10 includes multiple (twelve) push rods (one above each pocket 14 for pushing the compound 20 through the die halls or apertures 19 in the die half 11 into the mold die 10. The molding compound 20 under pressure from the press rods flows into the pockets 14 and over the semiconductor assemblies 12. The top surface of the lower die half 13 may also contain the molding frame 25 with pockets 14 to form the lower part of the encapsulation of the assemblies 12.
FIG. 5 illustrates a current mold press die machine with a single press rod 21 for all four molding sections 15-18 by a single die hall or center runner opening 19 centered in the die half 11 and by branching runners or channels 22 from the center runner 19 to the twelve pockets 14 for providing the forms for the encapsulation of the assemblies 12 on the substrate/leadframes 101-104. The branching runners 22 are grooved channels in the die half 11. In the case of symmetrical molding (above and below the substrate/leadframe) of the assemblies 12 the top surface of the die half 13 also has similar pockets 14 and runners 22. The arrows represent the flow of the mold compound 20. To perform encapsulation of multiple assemblies on multiple substrate/leadframes in a plane as shown in FIG. 5 takes a large pressure.
It is desirable to provide a mold press die machine that that handles multiple/lead frames that takes up less space and requires less pressure.